Ventilation and particulate matter removal system

ABSTRACT

a display adapted to provide to a user information on concentration of particulate matter leaving the internal space so that the operator can continue use of gas from the gas source to dislodge particulate matter in the internal space until a satisfactory value of the concentration is achieved.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national stage application, filed under 35 U.S.C.§ 371, of International Patent Application No. PCT/AU2019/000050, filedon 29 Apr. 2019, which claims priority to and the benefit of:AU2018901409, filed 27 Apr. 2018; AU2018903037, filed 17 Aug. 2018; andAU2019900979, filed 24 Mar. 2019. Each of the aforementionedapplications is incorporated by reference herein in its entirety.

FIELD

Apparatus systems and methods are disclosed for removal of particulatematter from enclosed spaces and enclosures, with particular reference toremoval of dust, dirt and the like from enclosed cabinets containingelectrical components.

BACKGROUND

In many industries, electrical, electronic and other sensitive equipmentis housed in enclosures designed to provide a safe and clean operatingenvironment for that equipment and to prevent unauthorized orinadvertent access. This can be the case in both fixed industrialinstallations and mobile equipment.

Although such enclosures are generally designed and maintained toprevent or limit ingress of particulate matter, for example dust anddirt, it has been found in some applications that enclosures dosometimes need to be cleaned out of such particulate matter. Failure todo so in these applications can eventually threaten proper operation ofthe electrical or electronic equipment.

For example, in the mining industry, haul trucks with diesel-electricdrives have enclosures (cabinets) for electrical components which aresometimes found to accumulate significant quantities of particulatematter, even when carefully maintained, but particularly with ageing andwhen maintenance is imperfect. Other mobile equipment used in thesurface mining industry, e.g. electric blasthole drills, shovels anddraglines may have enclosures that are similarly affected.

Cleaning out of particulate matter from such enclosures to a suitablestandard of cleanliness can itself be difficult and time consuming.Water cleaning is unsuitable for cleaning electrical and electronicequipment. Vacuum cleaning is often ineffective in removing particulatematter from spaces within and between components. The use of compressedair can create occupational, environmental and ecological exposure risksfrom airborne particulate matter.

It is believed that there are other areas of activity including forexample underground mining, and certain above-groundindustrial/manufacturing installations in which the above problemsoccur. In some of these, the particulate matter in question may beconsidered toxic either inherently because of its chemistry or becauseof factors such as particle size or shape or even the expectedsensitivity of persons likely to be exposed to the matter.

Disclosed herein are equipment, systems and methods for addressing theproblem of cleaning particulate matter from enclosed spaces.

In this specification, no reference to prior art or to what is known, isto be taken as a concession that anything is a part of the commongeneral knowledge in Australia or elsewhere.

DISCLOSURE OF THE INVENTION

In a first aspect the invention provides apparatus for removingparticulate matter from an enclosure having an internal space and anopening into the internal space, comprising:

-   -   a cover positionable adjacent the opening so that the cover        covers the opening;    -   a gas source external to the internal space;    -   an inlet conduit that in use extends through the cover and is        adapted to direct gas from the gas source to at least one gas        outlet within the internal space whereby particulate matter        within the internal space is dislodged and entrained in gas        within the internal space;    -   a source of partial vacuum adapted to maintain a partial vacuum        within the enclosed space and to draw gas and particulate matter        entrained therein from the internal space firstly through an        outlet conduit and then through a particulate matter separation        means comprising at least one filter;    -   a sensor for sensing concentration of particulate matter in gas        leaving the enclosed space;    -   a display adapted to provide to a user information on        concentration of particulate matter leaving the internal space        so that the operator can continue use of gas from the gas source        to dislodge particulate matter in the internal space until a        satisfactory value of the concentration is achieved.

Preferably the outlet conduit is in use secured to the cover and drawsgas through an opening in the cover.

Preferably the or at least one gas outlet is movable relative to thecover among multiple positions within the internal space.

Preferably the gas outlet is at an end of an elongate tubular lancecomprised in the inlet conduit, the lance in use extending though a portin the cover so that a portion of its length is in the internal spaceand the user can manually move the lance to cause the gas outlet totakes up any of the said multiple positions within the internal space.

Preferably the port in the cover is one of a plurality of ports in thecover so positioned that the user can withdraw the lance from one portand enter the lance into another port as required to access multipleparts of the internal space.

Preferably each of the plurality of ports has a restriction adapted torestrict flow of gas and particulates therethrough when the port doesnot have the lance extending through it.

Preferably, the apparatus further comprises control apparatus forstopping flow of gas from the gas source to the at least one gas outletby the user.

Preferably the control apparatus is operable automatically in responseto sensed pressure within the internal space rising to a predeterminedthreshold level to interrupt flow to the at least one gas outlet.

Preferably the apparatus further comprises a sensor for sensingconcentration of particulate matter in gas discharged from the apparatusdownstream of the source of partial vacuum.

In a further aspect the invention provides a method for removingparticulate matter from an enclosure having an internal space and anopening into the internal space, comprising the steps of:

-   -   positioning a cover adjacent the opening so that the cover        covers the opening;    -   providing a gas source external to the internal space;    -   providing an inlet conduit that in use extends through the cover        and is adapted to direct gas from the gas source to at least one        gas outlet within the internal space whereby particulate matter        within the internal space is dislodged and entrained in gas        within the internal space;    -   providing a source of partial vacuum adapted to maintain a        partial vacuum within the enclosed space and to draw gas and        particulate matter entrained therein from the internal space        firstly through an outlet conduit and then through a particulate        matter separation means comprising at least one filter;    -   providing a sensor for sensing concentration of particulate        matter in gas leaving the enclosed space;    -   using the sensor to derive and provide to a user information on        concentration of particulate matter leaving the internal space;    -   the user using gas from the gas source to dislodge particulate        matter in the internal space until a satisfactory value of the        concentration is achieved.

Preferably the method further comprises the steps of:

-   -   repeatedly sensing concentration of particulate matter in gas        leaving the internal space during cleaning thereof and making        into digital records thereof;    -   time stamping each digital record and transmitting using a        digital data network the digital records to a remote location        for recording and approval.

The method may include the step of repeatedly sensing pressure withinthe internal space during cleaning thereof and including in thetransmitted digital records sensed values of pressure within theinternal space.

Preferably the method includes the steps of:

-   -   further providing a sensor for sensing concentration of        particulate matter in gas discharged from the apparatus        downstream of the source of partial vacuum;    -   repeatedly sensing concentration of particulate matter in gas        discharged to atmosphere downstream of the source of partial        vacuum and including in the transmitted digital records sensed        values thereof.

Further embodiments and additional features and inventive concepts aredescribed in the following detailed description, based on the attacheddrawings.

Everywhere in this specification, the word “comprise” and derivativesthereof including “comprising”, “comprised” and the like, when used inrelation to items, elements or steps, are to be taken as indicatingpresence of those items elements or steps, but not as precluding thepossible presence of other items, elements or steps.

Everywhere in this specification, the terms “particulate” and“particulates” are to be understood as short and convenient terms forparticulate matter. It is further to be understood that the particulatematter described will in some applications comprise particles with arange of sizes. Except where otherwise stated, the terms “sealingly” and“gas-sealingly”, where used in this specification in relation to twoparts or elements, are to be taken to mean that gas and particulatematter entrained in that gas are wholly or substantially or at least toa useful degree prevented from leaking or passing between the two partsor elements.

BRIEF DESCRIPTIONS OF THE DRAWINGS

FIG. 1(b) is a perspective view of an enclosure being cleaned;

FIG. 1(a) is a cross-sectional view of the enclosure shown in FIG. 1(b)being cleaned;

FIG. 2 is a schematic diagram showing components of a cleaning systemaccording to an aspect of the invention and connections between thosecomponents;

FIG. 3 is a block diagram of instrumentation and control components;

FIG. 4 is a perspective view of a cabinet for electrical componentspartially modified to implement the invention;

FIG. 5 is a partial exploded perspective view of the cabinet shown inFIG. 4;

FIG. 6 is a perspective partially exploded view of an assemblycomprising a frame and door of the cabinet shown in FIG. 4;

FIG. 7 is a front elevation of the cabinet shown in FIG. 4;

FIG. 8 is a partial section of the cabinet of FIG. 7, the section beingtaken at station BB in FIG. 7;

FIG. 9 is an enlarged view of detail A of FIG. 8;

FIG. 10 is a sectional view of the cabinet as shown in FIG. 7, thesection being taken at station DD of FIG. 6;

FIG. 11 is a vertical section through an alternative port assemblyaccording to the invention, when in use;

FIG. 12 is a vertical section equivalent to FIG. 11 showing thealternative port assembly of FIG. 11, now when not in use.

FIG. 13 is a view exactly equivalent to FIG. 8 of a temporary version ofthe frame shown in FIG. 8;

FIG. 14 is a vertical section view of an enclosure fitted with atemporary cover according to an embodiment of the invention;

FIG. 15 is a side view of a cleaning lance according to the inventionfitted with a collar assembly;

FIG. 16 is a perspective view of a cabinet and a further cover assemblypositioned ready to be secured to the cabinet;

FIG. 17 is an elevation of a clamp assembly as shown in FIG. 16 and asseen looking in the direction of arrow “17”;

FIG. 18 is a cross-sectional view of a port assembly of the cover shownin FIG. 16

FIG. 19 is a perspective view of the port assembly shown in FIG. 18;

FIG. 20 is a sectional view of an enclosure showing a method of blowinggas according to the invention that is an alternative to that of FIG.1(a);

FIG. 21 is a sectional view of an enclosure showing an method of blowinggas according to the invention that is an alternative to that of FIG.1(a);

FIG. 22 is a side view of an open-topped railcar (whose upper section isshown in longitudinal cross-section) and a cleaning apparatus accordingto a further aspect of the invention;

FIG. 23 is a side view, with one portion shown in section, of anassembly of components of the system shown in FIG. 2;

FIG. 24 is a perspective view of a cabinet and a further cover assemblypositioned ready to be secured to the cabinet;

FIG. 25 is a longitudinal central section of a shipping container (withsome detail omitted) fitted with particulate removing equipment;

FIG. 26 is a longitudinal central section (equivalent to FIG. 25) of ashipping container (with some detail omitted) fitted with alternativeparticulate removing equipment;

FIG. 27 is a longitudinal central section of a barrel-type containerfitted with apparatus for removing particulate matter;

FIG. 28(a), FIG. 28(b), and FIG. 28(c) are a set of three schematicdiagrams showing different ways in which the apparatus and methodsdescribed herein may be applied;

FIG. 29 is an elevation of an exterior side of a further enclosure coveraccording to the invention;

FIG. 30 is a partial cross-section taken at station “30-30” in FIG. 29;

FIG. 31 is a partial cross-section taken at station “31-31” in FIG. 29;

FIG. 32 is a schematic view of an enclosure of components of theinvention and an enclosure being cleaned, these two enclosures beingconnected by a duct through which gas and particulate matter iswithdrawn from the enclosure being cleaned. The duct is shown insection;

FIG. 33 is a perspective view of yet another cover assembly according tothe invention;

FIG. 34 is an elevation of a portion of a prototype system according tothe invention;

FIG. 35 is an exploded view of the prototype portion shown in FIG. 34,now with a filter holder and screw cap removed as if for emptying offilter bag;

FIG. 36 is a perspective view of an elongate filter bag holder for usein the invention; and

FIG. 37 is a transverse sectional view of the holder of FIG. 36 in usewith a contained filter bag, the section being taken at station “A” ofFIG. 36.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The following description, based on FIGS. 1-3, is based for convenienceon arrangements and methods for cleaning particulates from cabinets suchas those used for containment of electrical and electronic componentsand the like. However, other arrangements and applications are disclosedsubsequently by reference to FIGS. 4-28, and it is to be understood thatthe same principles are applicable to them.

FIGS. 1(a) and 1(b) show schematically how an internal space 2 of acabinet (that is, an enclosure) 4 containing electrical (or other)components 6 can have accumulations of particulates removed.

A door 8 of cabinet 4 seals against fixed part 5 of cabinet 4 due to aseal 7 that extends peripherally around the edge of door 8. Door 8 hasat least one port assembly 10 through which a rigid, elongate cleaninglance 12 can be inserted so that a part of its length is in internalspace 2. Cleaning lance 12 is elongate and tubular and provided with gasfrom a source 32 (see FIG. 2) external to cabinet 4, the gas beingexpelled in a stream or jet from a nozzle 14, nozzle 14 being insideinternal space 2 during that part of the cleaning process shown in FIG.1(b). In some embodiments, cleaning lance 12 has a manually operablevalve 16 for control (including shutoff) of gas flow through nozzle 14.Blowing a stream or jet of gas into internal space 2, as shown in FIG.1(a), allows dislodgement of particulates from internal surfaces ofcabinet 4 and components 6 and agitation of dislodged particulates sothat they are entrained in gas within the internal space 2. Cleaninglance 12 can be manipulated by a user outside enclosure 4 so as to movethe stream of gas ejected from it inside enclosure 4.

Cabinet 4 also has at least one outlet port 18 through which gas andentrained particulates can leave internal space 2 and be drawn into aduct 20 by an external source (see item 46, FIG. 2) of at least partialvacuum. As will be described further below, at least some of theparticulates removed through outlet port 18 are removed from the gasdownstream of outlet port 18. Outlet port 18 is shown as comprised indoor 8, but may in alternative embodiments (not shown) be comprised infixed part 5 of cabinet 4. The position of the outlet port is selectedto benefit from gravitational settling and stratification of the dust sothat the dust can be extracted as completely as possible. Further, anextension duct (not shown) may be fitted to the outlet port 18 to movethe location from which gas and entrained particulates further into theenclosure 4. (This approach may also be taken in other embodimentsdescribed below.)

Cleaning lance 12 can be manually oriented (as shown by arrows 15), andthe extent of its penetration into space 2 varied (as shown by arrows17) , by a user of cleaning lance 12 to orient and position nozzle 14 tobest effect for dislodging particulates. Door 8 is provided with atransparent viewing window 22 so that the cleaning lance 12 in internalspace 2 can be seen during cleaning. The purpose of providing multipleports 10 is to enable a user to withdraw cleaning lance 12 from one port10 and then insert it into another port 10 so as to dislodgeparticulates in multiple locations in internal space 2.

Cleaning lance 12 is a gas discharging device and essentially comprisesa gas flow control valve 16 for manual operation by a user and anelongate tube 13 through which gas leaving valve 16 passes to nozzle 14from which it issues in a gas stream or jet. Nozzle 14 may be of anysuitable form or may be omitted altogether so that gas simply issuesfrom an open end of tube 13. Nozzle 14 may direct gas at an angle to thelength of tube 13, for example, or may even be freely rotatable about alengthwise axis of tube 13 and expel gas at an angle to tube 13 suchthat reaction force from the gas stream causes the nozzle 14 and itsemerging jet of gas to rotate. Nozzle 14 may optionally simply comprisean open end of tube 13, but in other embodiments would comprise afixture that causes gas to increase in speed (hence momentum) as itleaves tube 13. Such a nozzle 14 may be detachable from tube 13.

In use of the method and apparatus illustrated in FIG. 1(a), particulatedislodgement and removal from the internal space 2 is continued untilthere is a satisfactorily low concentration of particulate matterentrained in the gas leaving the internal space 2. As set out below, asensor for such concentration is provided, and information on theconcentration is provided to a user so that cleaning can cease when theconcentration is low enough. By maintaining a pressure in the internalspace 2 that is lower than the atmosphere outside the internal space 2,leakage of particulate around the door 8 or through the ports 10 duringthe cleaning operation is limited or prevented. Concentrationmeasurement provides an objective criterion for ending the cleaningprocess.

While the methods of FIGS. 1(a) and 1(b) have been illustrated byreference to an enclosure 4 with modifications to its door 8, there willbe described below embodiments in which a temporary cover is placed overan opening of an enclosure having an internal space instead of a door.

FIG. 1(b) shows another mode for particulate removal from internal space2. Door 8 has been opened and particulates are being drawn into a duct24 by the above (or a second) partial vacuum source. Particulate removalin this way may be done before or after a period of particulate blowingas shown in FIG. 1(a) as found appropriate or between periods ofparticulate blowing.

In some applications, it is appropriate to remove significantaccumulations of particulates first by the method shown in FIG. 1(a) andthen through use of the conventional vacuuming approach of FIG. 1(b).

Although FIG. 1(a) shows all port assemblies 10 to be provided in door8, it is possible to provide port assemblies (not shown) in other parts(e.g. top, bottom or side walls) of cabinet 4.

The gas may be air in suitable cases or may be an inert gas such as (forexample only) nitrogen or carbon dioxide (derived for example from dryice). Inert gas may be appropriate where fire, explosion or chemicalreaction is a potential hazard.

FIGS. 2 and 3 show schematically an embodiment of a cleaning system 30that is operable as described above to remove particulates from theenclosure 4. System 30 includes an instrumentation and control system199 that is not shown in FIG. 2, but whose functionality is illustratedseparately and schematically in FIG. 3.

Referring firstly to FIG. 2, a gas source 32 is provided to direct gasto nozzle 14 through a conduit 34 which includes both a flexible hoseportion 33 and cleaning lance 12. Where air is to be the gas, gas source32 may comprise, for example, a pump or blower (centrifugal or axial ora hybrid of these) or a reciprocating-piston compressor or a containerof compressed air. In some applications and facilities, a reticulatedcompressed air supply (not shown) may be available and a connectionthereto can constitute gas source 32. Gases other than air may be used,being stored as a gas, or as a liquid or solid that changes phase on orbefore discharge, or generated by chemical reaction.

Conduit 34 may comprise flexible hose to enable manipulation of thecleaning lance 12.

Item 52 in FIG. 2 represents one or more components for conditioning andcontrolling the gas supply to lance 12. It is preferred that the gassupply is conditioned to be substantially oil- and moisture-free, andcomponents are known in the art for achieving this. More will be saidabout item 52 below.

Gas and entrained particulates are drawn out of enclosure 4 through duct20 connected to enclosure 4 at outlet port 18 and then through a cycloneseparator 38 (of which one is shown, but multiple cyclones may be usedif appropriate to a particular application) and filters 40 and 42 by ablower 46. Together the cyclone 38 and filters 40 and 42 removeparticulate matter to a desired standard (particle size andconcentration). One or more of the filters 40, 42 may be a “HighEfficiency Particulate Air” (HEPA) filter. Although two filters 40 and42 are shown in FIG. 2, this is not intended to be a limitation. Morethan two filters may be used, or in suitable cases even one filter onlyor no filter at all. Duct 20 may comprise a length of suitable flexibleducting. Where duct 20 comprises a flexible material reinforced with aspiral wire, or otherwise comprises conductive material along itslength, that wire or conductive material may be preferably earthed tolimit explosion risk when battery power is used for the system 30.

To draw gas and entrained particulates from the enclosure 4, a vacuumsource, such as a suitable fan or blower 46 is provided so that pressurein duct 20 is reduced. As shown in FIG. 2, this may be locateddownstream of the cyclone 38 and filters 40 and 42.

To also enable direct vacuuming of particulates from enclosure 4 asshown in FIG. 1(b), duct 20 may be disconnected from outlet port 18 andused as vacuum hose 24. Alternatively, as shown in FIG. 2, a separateduct 48 may be provided that is connected to duct 20 via a selectorvalve 50 and used as duct 24. Selector valve 50 allows selection ofdirect vacuuming through duct 48 (as in FIG. 1(b) or removal of gas andentrained particulates as in FIG. 1(a). Duct 48 is shown with an endfitting 47 for increasing the flow velocity of flow into duct 48. Such afitting may also be used (not shown) with duct 20 if duct 20 is used asduct 24 for direct vacuuming.

Selector valve 50, where provided, may be adapted to ensure that somesuction is maintained in duct 20 even when duct 48 is in use.

In some embodiments, end fitting 47 may be of the same or similar formas lance 12, so as to be enterable into any of ports 10 and enabledirect vacuuming of particulates with door 8 closed. In still furtherembodiments lance 12 itself is provided with an inlet for gas from thegas source 32, as above, and additionally with a connection for duct 48,allowing either suctioning via duct 48 or blowing with gas from gassource 32. In such embodiments valve 16 comprises a selector forenabling sucking or blowing.

Still another alternative to the arrangement mentioned in the previousparagraph is to use a separate vacuum cleaner (not shown) for directvacuuming in cabinet 4.

Depending on the intended capacity of the system 30, some or all of thecomponents shown to the left of station “XX” in FIG. 2, includingrelevant parts of instrumentation and control system 199 may be providedin a single enclosure. This may be a fixed installation (not shown), orwheel or skid-mounted (not shown), or even comprised in a backpack-typeenclosure. In some embodiments, as stated above, gas supply 32 is simplya connection to a reticulated compressed air supply. It has beenconfirmed by applicants that a version of system 30 adequate for use incleaning particulates from electrical cabinets of large diesel-electricmining haul trucks can be implemented in an enclosure the size of asmall-to-medium suitcase.

Instrumentation and control system 199 will now be described, stillusing the electrical cabinet cleaning application shown in FIG. 1 forillustrative purposes. (Some other applications mentioned below may notrequire all the functionality described.) Locations in the system 30which may be provided with sensors of various types are labelled A to Lin FIG. 2.

FIG. 2 is not intended as a detailed indication of hardware componentsand their connections. It is intended to explain what the system 199does. The functions are straightforward enough for persons of ordinaryskill in the art to implement without more specific detail.

Sensors and associated signal conditioning may be provided in system 30for the following purposes:

-   -   (a) to ensure that when particulates are being removed by        entrainment, as in FIG. 1(a), it is able to be known when a        satisfactorily low concentration of particulates is entrained in        gas being drawn from the enclosure being cleaned (e.g. cabinet        4), (whichever one of port assemblies 10 is in use) so that that        process is complete;    -   (b) to enable monitoring of gas leaving blower 46 to ensure it        has a satisfactorily low concentration of entrained        particulates, so that persons near the point of discharge of gas        leaving blower 46 are protected from harm;    -   (c) to enable monitoring of the operation of the various        particulate-separation components of the system 30 and so ensure        that filters 40 and 42 and cyclone 38 (in particular) are        cleaned or emptied when appropriate and blower 46 cleaned if        necessary;    -   (d) to ensure that components 6 in the enclosure being cleaned        (e.g. 4, 60) and blower 46 are not exposed to unsafe/damaging        temperature levels;    -   (e) to enable monitoring of pressure in the enclosure 4 being        cleaned to ensure it remains in a range where there is neither        damage to the enclosure 4 nor leakage of particulates from the        enclosure 4, in particular by maintaining pressure in the        enclosure below atmospheric pressure in the surroundings where        work is being carried out;    -   (f) to enable monitoring of the position and/or functioning of        the seal 7 and door 8; and    -   (g) to provide necessary inputs for automatic control of parts        of the system 30;    -   (h) to enable remote (or local) monitoring of the condition of        the various parts of the system, so that maintenance and        servicing can be carried out in a timely fashion.

Depending on requirements of particular applications and users,embodiments may comprise sensors for all or some only of these purposes.Outputs from the sensors can be used in some or all of the followingseveral ways, as follows:

First, sensor outputs may be displayed directly as numericalmeasures—for example, pressure or blower 46 temperature in the enclosurebeing cleaned may be displayed on a suitable display. Alternatively,they can be displayed as “OK/Not OK” visual signals—for example it maybe sufficient to indicate that a connected gas supply has pressureenough to be used rather than display its actual value.

Second, numerical quantities may be computed from sensor outputs anddisplayed—for example flow rate of gas through fan 46 or cleaning lance12. Derived quantities also may be provided only as “OK/Not OK” visualindications.

Third, audible or visible alarms can be generated where necessary anddiagnostic messages displayed to guide correction by users. Further,alarm conditions may be used to trigger an automatic shutdown orotherwise limit operation of the system, i.e. to provide a “fail-safe”capability.

Fourth, sensor outputs and quantities derived from them may be recordedby a data logging facility, for verification or diagnostic purposes. Fordata logging, time stamping of data may be provided and even locationmay be recorded by provision of a GPS module. This use of sensor outputsis particularly important where it is desired not only to cleanenclosures but to ensure that there is proof and/or certification of thestandard of cleaning that has been carried out. This is potentiallyvital in applications where diseases such as silicosis, “black lung”disease and diseases associated with asbestos are to be avoided, forexample. Further, purpose (h) above becomes very important inapplications where logged data is to be provided to an off-siteorganisation for monitoring/certification purposes. Only if theequipment's condition can be maintained properly can results be reliedupon.

Fifth, as well as the fail-safe capability mentioned above, automaticcontrol of parameters and components may be provided using sensoroutputs, as discussed below.

Particular choices from the above can be made according to intendedapplications.

Regarding purposes (a) and (b) above, the extent of particulateconcentration in gas flows can be sensed using triboelectric particulatesensors. These are available from suppliers such as Auburn FiltersenseLLC of Beverly, Mass., USA. While triboelectric-type sensors aresuitable, other types are known in the instrumentation art and can beused as appropriate, for example sensors based on interruption orattenuation or transformation of a beam or beams of infra-red radiation,visible light, laser, beta rays or other EMF or nuclear radiation byparticulates, or even acoustic-type sensors (in effect microphones)which react to impacts of particulates on a surface. The appropriatechoice will depend on the particular application at hand.

Thus, to achieve aim (a) above, there may be provided one or moretriboelectric (or other suitable) sensor(s) at station F (or a positionupstream of it, or even inside space 2),

To achieve purpose (b) above, there may be provided one or moretriboelectric (or other suitable) sensor(s) at station K, downstream ofthe cyclone 38, filters 40 and 42 and blower 46. In some embodiments, aduct (which may be flexible) may be provided to take discharged gas andresidual (i.e. unremoved) particulate well away from the area in whichthe cleaning operation is taking place.

Depending on the gas source, it may be appropriate to provide sensing ofgas quality upstream of cleaning lance 12, for example at stations A orB. At station A, a pressure sensor may be provided to indicate, whencleaning lance 12 is not in use, that gas for blowing is available.

Regarding purpose (c) above, pressure sensors (not shown) may beprovided at stations G, H and Ito provide a measure of fouling offilters 40 and 42 with particulates, based on pressure drop throughthem, so that the need for cleaning can be indicated at an appropriatetime. Rather than three such separate sensors, two differential pressuresensors (not shown) may be provided, respectively sensing pressuredifferences between stations G and H and H and I.

Similarly, in some embodiments either another sensor (not shown) isprovided to measure the pressure difference between stations F and G,before and after the cyclone 38, or alternatively separate sensors atstations F and G can be provided. Excessive pressure difference acrosscyclone 38 can indicate fouling or blockage.

It is also possible to provide a pressure sensor at station K inaddition to a pressure sensor at station I, so that the pressure changethrough blower 46 is known, or alternatively to provide a differentialpressure sensor to sense the pressure change between stations I and K,i.e. across blower 46. The speed of blower 46 may be sensed at station Jas well.

Also in relation to purpose (c), at station L, a sensor (not shown) maybe provided to indicate that a certain quantity of particulates has beencollected in cyclone separator 38 (or a particulates container (notshown) secured thereto), so that for best operation, cyclone 38 shouldbe emptied. This may be of the optical or infra-red type, that sensesinterruption of a beam, these sensors being well known in theinstrumentation art. Alternatively an ultrasonic type may be used, oreven a simple “sight-glass” type indicator or transparent section ofcyclone 38 may be provided that can be seen by a user. When a“sight-glass” type indicator is used, an LED light positioned andcoloured to minimize glare may be used internally within the cyclone 38or particulates container to enhance visual clarity.

Regarding purpose (d) above, in some embodiments, temperature of theblower 46 is sensed at station J and/or temperature of gas within space2 is sensed at station C (or even F), in each case with suitabletemperature sensors.

Regarding purpose (e) above, during use of cleaning lance 12, it isdesirable that gas pressure in cabinet 4 be maintained at a level thatdoes not lead to significant risk of particulates leakage from thecabinet 4 through for example port assemblies 10 or past seal 7 arounddoor 8. A pressure in cabinet 4 slightly below external (atmospheric)pressure is suitable in many applications, as it limits the potentialfor leakage of particulates from cabinet 4.

It is also desirable that during the blowing operation, pressure incabinet 4 not become too high or too low, to avoid distortion or evenstructural failure of cabinet 4. A simple approach is to provide apressure sensor (not shown) at station C (i.e. sensing absolute pressurewithin space 2 of cabinet 4, or the difference between the pressureinside space 2 and the atmosphere). Actual control of the pressure inspace 2 is described below. The pressure sensor (not shown) may belocated physically on the cabinet 4 or on door 8 with signalscommunicated to instrumentation and control system 199 via copper cable,optical fibre, wireless or other suitable means. Alternatively, thepressure sensor may be mounted away from the cabinet 4 and communicatewith space 2 via a small-bore flexible tube.

Regarding purpose (f) above, it is important when blowing gas into anenclosure such as cabinet 4 that there be no leakage of air (andentrained particulates) past elastomeric seals such as seal 7 of cabinet4, due for example to seal 7 failing to close off excessive gaps betweendoor 8 and cabinet 4 at positions along the seal 7. For applicationssuch as that shown in FIG. 1), where a hinged door 8 is sealed by seal7, a single sensor (not shown) may be provided to sense whether the door8 is in the correct position, relative to cabinet 4, for correctoperation of seal 7. This could be a simple microswitch or a proximitysensor mounted to door 8 or cabinet 4. If seal 7 is a pneumatic (i.e.inflated) seal, a pressure sensor may be provided to sense pressure inthe seal 7.

However, in some embodiments described below, a detachable cover (seefor example item 310 in FIG. 16, item 310 a in FIG. 24, item 310 b inFIG. 33, item 310 c in FIG. 29) is used to close off an enclosure orspace. In these cases, multiple proximity or other suitable sensors (notshown) may be provided at spaced-apart positions around the coverperiphery to enable monitoring of seal operation. These sensors may beof proximity type as above, or be responsive to pressure between theseal and enclosure or electrical conductivity between metallic areas oneither side of the seal and facing parts of the enclosure or cover. Thesensor locations would correspond for example to stations D and E inFIG. 2.

If measurement of gas flow rate to lance 12 is required, a flow meter(not shown) may be provided at station B. This could be of any suitabletype, for example a venturi section or calibrated orifice plate withsensor(s) to measure the pressure change therethrough (and ideallytemperature as well), or a sophisticated thermal sensor such as thoseavailable from E+E Elektronik GmbH of Germany. Also, and in the same orany other suitable way, the gas flow rate out of space 2 may bemeasured. This may be done at station I or station K, where themeasurement is unlikely to be influenced by entrained particulates. Forapplications where concentrations are expected to be sufficiently small,outlet flow rate measurement may be made with sensors at any of stationsF, G, H or I.

Regarding purpose (g) above, control of the blowing/entraining operationwill now be described.

In some embodiments, gas flow to the cleaning lance 12 from supply 32 issimply turned on or off as required, by a user, with blower 46 runningcontinuously. The user, as well as monitoring the extent of particulateconcentration (visually, or by use of particulate concentrationsensor(s) as described above) can monitor pressure in the space 2 ifdisplayed, or simply be alert for alarms based on the sensed pressure inspace 2 being, or threatening to be, out of a specified range.

A more sophisticated approach in other embodiments is to include in item52 (FIG. 2) a solenoid valve that can interrupt (or vent to atmosphere)gas flow to cleaning lance 12 automatically if required to preventoverpressure (or loss of appropriate partial vacuum) in space 2.Similarly, blower 46 can be stopped automatically or slowed down, (or adamper operated) if required to prevent an excessively low pressure inspace 2. The system 199 generates signals to control the blower 46and/or solenoid valve in item 52, based on sensed pressure in space 2 ora mismatch of inlet and outlet flow rates.

For either of the approaches described in the previous two paragraphs,generation of an alarm and/or of automatic control signals can beanticipatory, based on rate of change of pressure or gas flow rates.

In still other embodiments, closed-loop automatic control is used,subject to maintenance of a “fail-safe” capability. For example,cleaning lance 12 may be manually controllable by a user (i.e. with gasflow rate set to off, fully on, or any intermediate value), with blower46 and/or a variable-flow valve included in item 52 controlledautomatically by system 199 to maintain a chosen value (i.e. set point)of pressure in space 2 or net gas flow rate into space 2. Alarms and/ordisplay of operating parameters may be provided also in theseembodiments. For further example, cleaning lance 12 may be simply set to“off” or “fully on”, with closed loop control of a set pressure in space2, net flow rate into the space 2, or a specified flow rate throughlance 12.

Referring now to FIG. 3, block 200 represents one or more componentsadapted to provide the functionality described herein. It is to beunderstood that block 200 may simply comprise a single processor(microprocessor or otherwise) or several processors each covering asubset of the functions required. For example, if there is a closed-loopcontrol functionality as described herein, that may have a dedicatedprocessor. Some or all of the functions carried out within block 200 maybe implemented wholly or partially by other means thanmicroprocessors—for example field-programmable gate arrays (FPGAs) maybe used to implement some functionalities. Multiple data processingcomponents may be comprised in block 200, for example, where avariable-flow valve is included at item 52 and has its own internalelectronics or where a particulate concentration sensor is provided thathas its own data processing components.

The data processing componentry of block 200 is provided to receiveinputs from sensors and system controls and, using these, to drive adisplay at 208, and/or a set of alarms at 210 and, as applicable,control outputs at 207. It may not be essential for a particularapplication or embodiment to provide and use all of the sensorsdescribed above. For example, in some embodiments reliance may be placedon visual inspection of cyclone 38 to determine that it needs emptying,rather than providing a sensor at station L. However, in general somesensors will be used, and block 202 represents a set of sensorexcitation (i.e. powering) and any necessary signal conditioningfunctions, all as required to convert raw signals from the sensors to aform (digital or analog) suitable for the processing function 200. (Notethat many processors have internal analog-to-digital converters and socan accept analog signals.) The triboelectric sensors of the prototypesystem described below provide outputs in current-loop form, while thepressure transducers provide digital outputs directly.

Block 204 represents presentation of sensor outputs to the processor at200. For example in the prototype system described below, a multiplexeris used to provide 8 scannable channels for pressure sensors via the 1²C bus protocol. Multiplexing of sensor outputs may be provided if thereare more sensors used than the number of inputs provided by the chosenmicroprocessor 200. Note that as discussed above there may be severalsensors at some stations, for example a pressure sensor and atemperature sensor at station C. FIG. 2 is not intended to suggest amaximum of 12 sensors (A-L). Block 200 may also include any or all of:automated fault detection, diagnostics and datalogging capabilities.

System 30 also requires some control inputs provided at block 206 suchas on/off switches (not shown) for the blower 46 and the gas supply 32if it includes a dedicated compressor for example, and to initiateoperation of data acquisition by system 199. If any quantity is to becontrolled in closed-loop manner, there may be a control (e.g.potentiometer) to provide a set point for the mass flow rate. There mayalso be controls (e.g. potentiometers in the case of analog controlimplementation) to set allowed maximum and minimum pressures in theenclosure to be cleaned.

Block 207 represents provision of signals required for automaticfunctions—for example shutting off the gas source 32 if pressure atstation C rises too much or a continuous control signal whereclosed-loop pressure control is provided.

Block 208 represents provision of the function of one or more suitabledisplay(s) for visual output of system 30 information as required. Forexample, there may be display of outputs for particulate concentrationfrom triboelectric sensors at stations F and K. Displays (not shown) mayuse any suitable technology, for example LED,

LCD or OLED. The two last of these may be of a touch screen typearranged to receive any or all of the inputs mentioned in relation toblock 206 above.

Block 210 represents provision of a separate display of alarm conditionsfor system 30. For example, it may indicate that cyclone 38 requiresemptying or that filters 40 or 42 have pressure drops indicating thatthey need cleaning, or that pressure in the enclosure being cleaned isoutside its set limits, risking damage or particulates leakage. Suchalarm functions may actually be incorporated in and displayed on thedisplay 208, or may be provided separately, for example using a known“traffic light” format (not shown) based on green, yellow and red LEDsto indicate respectively—no alarm or normal operation, warning, alarmcondition.

The following is a list of conditions and responses that may beautomatically recognized and caused within block 200 to generate alarmsor control signals that provide system 30 with a “fail safe” capability.

-   -   Excessive particulate contents at either inlet or outlet of        blower 46—shut down blower, provide diagnostics.    -   Where intention is to operate at negative pressure—pressure        excessively low (with risk to structure) or not low enough        (risking leakage of particulates). If not low enough, interrupt        flow into the enclosure, also check blower, filter(s) cyclone        fouling. If too low either stop blower or reduce blower speed.    -   Where positive pressure in enclosure 4 is allowed—pressure        excessively high risking structural damage or leakage of        particulates. Interrupt flow into enclosure, increase blower        speed, check for fouling of filter(s) or fouling or filling of        cyclone(s).    -   Fouling of filter(s)—stop operation of system.    -   Fouling or filling of cyclone(s) 38—stop operation of system.    -   Blower 46 temperature excessive—stop operation of system.    -   Blower 46 not operating or underspeed—stop operation of system.    -   Where seal 7 is a pneumatic seal—seal pressure out of allowable        range—stop operation of system.    -   Where seal 7 is pneumatic or non-pneumatic—any one or more of        seal position measurements (if sensors fitted) out of allowed        range. (Or if pressure sealing pressure sensor(s) fitted, any        one or more of their outputs out of range. Stop operation of        system.

Block 211 represents the writing of sensor and other data to some formof storage. For example, the prototype system described below isprovided with a facility to write data based on sensor outputs to an SDcard for later downloading and checking. In that system, all activesensors are scanned cyclically once the system is in operation andderived outputs from them are time stamped using a real-time clockmodule and written to an SD card.

Block 213 represents communication of data to location(s) away from theworksite and receipt of instructions and/or the like from externalsources. For example, where a service provider wishes to providechecking and certification of critical particulate removal operationsfrom a location away from the site of the operation, it is possible toprovide a communications interface for the transmission and receipt ofdata and instructions. As an example, a mine may have a wirelesspacket-switched digital data network covering its entire site that canbe used to communicate with a base station, and that base station maycommunicate via the mobile phone network or via the internet by whateverother connection means is available. Where mobile phone networkaccessibility is available at a worksite, it may be used and the basestation may not be necessary. The service provider may carryresponsibility for correct functioning, calibration and the lie for theequipment used for particulate removal, and receipt of data from thevarious sensors described facilitates this function. Data andinstructions may be transmitted substantially in real time or data maybe written to memory (e.g. using an SD card) by system 199 for latertransmission.

Note that although the above disclosure has referred to particulateremoval, it is possible to use the apparatus as shown in FIGS. 1(a), 2and 3 for purging of gases from enclosed spaces, either as analternative to particulate removal or in any application where bothparticulates and undesired gas are both present. An online gas analysisdevice suited to the gas in question may be provided at for example anyof stations F, G, H, I or K, instead of or in addition to a particulateconcentration sensor.

Ways to arrange for the methods of FIGS. 1(a) and 1(b), and theoperation of system 30 (including system 199) to be applied to otherenclosures will now be described.

FIGS. 4 to 10 show one way in which a typical existing cabinet 60 forelectrical components (not shown) can be modified to implement theinvention using cleaning system 30, cabinet 60 corresponding toenclosure 4 in FIGS. 1 and 2. Cabinet 60, is a cabinet such as mighttypically be found in an industrial facility or in heavy mobileequipment such as a locomotive or mining haul truck, and has a fixedmain portion 62 defining enclosed upper and lower spaces 64 and 66respectively for electrical components. Cabinet 60 has been modified toenable cleaning of particulates using the invention, but only in respectof the upper space 64.

Closure of opening 68 of lower enclosed space 66 is provided by aconventional hinged door 70 normally held closed by a handle-operatedlatch 72. A peripheral elastomeric seal 74 mounted to main portion 62extends around opening 68 to limit ingress of contaminants such asparticulates when door 70 is closed.

Normally, cabinet 60 would have a hinged door essentially the same asdoor 70 except for its dimensions being suited to close opening 76 ofupper space 64, and also a similar peripheral sealing arrangement.However, according to the modification, a rectangular frame 78 issecured (for example by welding at 81) to main portion 62 and extendsperipherally around opening 76 of the upper space 64. A hinged door 80is supported on frame 78 and can be opened to allow access to upperspace 64 when required. Door 80 is received in frame 78 and held closedby handle-operated latches 82, and contaminant ingress and between door80 and frame 78 is limited by a peripherally extending elastomeric seal84. Because cleaning can involve temporarily increasing pressure inupper space 64, door 80 includes a reinforcing member 79 extendingaround its periphery.

Door 80 has features that enable the invention to be implemented forcleaning of upper space 64.

First, door 80 is provided with port assemblies 86 (corresponding toport assemblies 10) through any of which cleaning lance 12 can be pushedpartway into upper space 64 at in the way shown for enclosure 4 in FIG.1(a). Door 80 also has a transparent viewing window 88 corresponding towindow 22 in FIG. 1(a).

Second, for removal of particulates from upper space 64, at least oneoutlet port 90 (corresponding to outlet port 18 in FIG. 1(a)) for gasand entrained particulates is provided in door 80. This has a removablecover 92 that can close outlet port 90 when cleaning is not underway.Duct 36 is secured to outlet port 90 for use when cleaning upper space64. Outlet port 90 is provided in door 80, however in some embodiments(not shown) it may be provided (or an additional outlet port may beprovided) at a suitable location in cabinet main portion 62.

In FIG. 6, one of port assemblies 86 is shown in exploded fashion. Oneor more discs 94 of gas impermeable elastomeric material (for exampleformed from an artificial or vulcanized natural rubber) are provided,each with a slit 96 extending across part of a diameter, and discs 94are arranged in layered fashion with slits 96 oriented in differentdirections as shown. Discs 94 are secured against the door 80 by a ring98 using fasteners (not shown) extending through holes 100 in ring 98and door 80, ring 98 being concentric with a hole 102 in door 80. Portassemblies 86 can be reasonably (not absolutely) gas- andparticulates-tight when not in use. Cleaning lance 12 can be pushedthrough slits 96 so that its nozzle 14 is inside the enclosure, whilethe gas supply hose 34 remains outside cabinet 60. Moreover, cleaninglance 12 can be rotated about its length as required, its angle to thedoor 80 varied, and the distance beyond door 80 to nozzle 14 can bevaried by a user as required. The number of port assemblies 86 on door80, and their positions, may in some embodiments be chosen to suit thearrangement of components within the enclosure 60 to enable mosteffective and thorough cleaning.

Note that the use of frame 78 as shown in FIGS. 4 to 10 is a measurethat was adopted for the particular cabinet 60 described here, which hadinadequate gas and particulates sealing around door 80. For a cabinetand door having adequate sealing arrangements (not shown) the doorfeatures described above may be able to be implemented by simplymodifying the original door.

As shown in FIG. 15, the cleaning lance 12 may have a collar assembly170 securable in any of a range of positions on tube 13 so as to preventexcessive penetration of cleaning lance 12 into the enclosure (forexample cabinet 60, cabinet 150 or enclosure 4), leading to potentialdamaging of components therein.

Alternatives to the port assemblies 10 shown in FIGS. 4 to 10 arepossible. One such is shown in FIGS. 11 and 12. FIG. 11 shows a portassembly 200 secured to an enclosure door 202 (similar for example todoor 80 or door 8) and providing access for cleaning lance 12 to aninternal space 204. Port assembly 200 comprises an elastomeric bellowsor boot 206, secured to door 202 by a ring 208 and fasteners 211.Secured to bellows 206 is a block 210 through which, in use, tube 13 ofcleaning lance 12 can pass. Tube 13 can slide lengthwise in, and rotaterelative to, block 210, and be angled in horizontal and vertical planesas shown by arrows 214, and sealing between tube 13 and block 210 isprovided by an elastomeric 0-ring seal. Other seal arrangements may beused depending on the application (e.g. lip seals, multiple seals). Whenport assembly 200 is not in use, a lid 216 is screwed onto a threadedportion of ring 208, after withdrawal of tube 13, to prevent gas andparticulates egress. (Note that a lid (not shown) equivalent in functionto lid 216 could be screwed to block 210 instead of ring 208.) Portassembly 200 requires that any nozzle 14 comprised in cleaning lance 12be of lesser diameter than tube 13, so that tube 13 can be enteredthrough block 210.

Further alternatives to the arrangements that were described above byreference to FIGS. 4 to 10 will now be described.

FIGS. 4 to 10 showed a permanent modification to an existing cabinet 60to implement the invention, in which a frame 78 was secured to a mainportion 62 of the cabinet 60, the frame 78 itself incorporating a door80. Another approach applicable to cleaning of cabinets with hingeddoors will now be described. This is to provide a temporary cover whichcan be secured sealingly over the opening of the cabinet after eitherremoving or swinging open the cabinet's existing door.

FIG. 13 shows in a view equivalent to FIG. 9 a temporary cover 77comprising a frame 78 a that is exactly the same as frame 78 in allrespects, including provision of a door 80 a equivalent to door 80,except that frame 78 a lacks a member equivalent to member 83 (see FIG.9) secured to cabinet portion 62 at 81. Instead, a retaining memberextending peripherally around frame 78 a is provided together with anelastomeric seal 87, also extending peripherally around frame 78 a. Whenparticulates are to be dislodged by use of cleaning lance 12, cover 78 ais temporarily secured to cabinet main portion 62, being held in placeby suitable clamps (not shown), the original door (not shown) of cabinet60 being swung aside or removed altogether. Seal 87 may be inflatablewith a gas to enhance its sealing action. When cleaning is complete,frame 78 a is removed.

FIG. 14 shows a view (in vertical section) of a cabinet 150 fitted withan alternative temporary cover 152 for cleaning. Cover 152 is secured bysuitable clamps 154 on its periphery. Cover 152 is sealed againstcabinet 150 by a peripheral seal 156. This may if desired be of a typeinflatable by gas. Cover 152 has port assemblies 158 which may be thesame as port assemblies 10 and a gas-and-particulates outlet port 160for connection of duct 20. Cover 152 has a dished shape (as seen in thesection of FIG. 14) to provide more room between the port assemblies 158and components 162 in cabinet 150 than would be provided by for examplecover 78 a. Where practicable, this shape can be advantageous inenabling easier and better positioning of cleaning lance 12 and reducedrisk of contact with and damage to components in cabinet 150. Further,cover 152 is formed from a substantially transparent plastics material(e.g. polycarbonate or acrylic) to provide for easy visibility of thecabinet interior while cleaning lance 12 is in use. Anti-scratchtreatments are known in the art and may be applied to at least theinward surface of cover 152. Still further, a set of light-emittingcomponents (e.g. LEDs) is provided inside the space 164 formed bycabinet 150 and cover 152 to enhance visibility within space 164. (Thisapproach to lighting is applicable also to other embodiments, such asthose shown in FIGS. 4 to 10 and 13.) Cover 152 is shown without a doorequivalent to door 80 a of cover 77 but a hinged door could be providedin cover 77 if desired (not shown).

FIG. 16 shows still another temporary cover 310 that is an alternativeto those described above. A cabinet 300 whose internal space 302 is tobe cleaned of particulates. Cabinet 300 has a flange 304 surrounding anopening 306 that in ordinary use of cabinet 300 would be closed by adoor or other cover. (No such door or cover is shown in FIG. 16.) Hinges308 could for example support such a door that either is simply swungopen or removed from cabinet 300. To cover opening 306, cover 310 isprovided.

Cover 310 has a formation 312 on its upper edge 314 that can be hookedover an upper part of flange 304 when cover 310 is moved in thedirection of arrows 305 towards flange 304. Cover 310 is then held inposition over opening 306 by clamps 316. Extending around the peripheryof cover 310 is a seal 318 that in use of cover 310 bears sealinglyagainst flange 304 to prevent or limit passage of particulates frominternal space 302 during cleaning (similarly to seal 84 of FIG. 8).Seal 318 is of rubber or a rubber-like material and may optionally be ofa pneumatic type inflated with a gas. (A seal (not shown) serving thesame purpose as seal 318 may, in alternative embodiments, be provided onan enclosure being cleaned for use with a cover otherwise equivalent tocover 310. Further, such a cover or a cover with a seal such as cover310 may instead of being hung from a flange (such as flange 304 in FIG.16, be hung from a suitable temporary or permanent formationspecifically provided.)

FIG. 17 shows one of the clamps 316. This has a magnet 322 that in useholds itself against surface 307 of cabinet 300, and captive thereon abolt 324 passing through cover 310. A wingnut 326 can be screwed on bolt324 to move cover 310 towards surface 320. Bolt 324 passes through acompression coil spring 325 between the magnet 322 and cover 310 to aidcorrect positioning of magnet 322 when cover 310 is being positionedready for use.

Any other suitable clamp arrangement can be used as an alternative toclamps 316. In other embodiments, where control of pressure within anenclosure being cleaned is sufficiently reliable, to maintain a negativepressure within that enclosure at all times and dispense with some orall clamps such as clamps 316. The cover 310 is then held in placeentirely or partially by atmospheric pressure due to the lesser pressureinside the enclosure. Another approach(not shown) as an alternative toclamps 316 is to provide magnetic tape to cover 310 extending around allor part of the periphery of cover 310 so as to be attracted to (forexample) flange 304. Still another approach (not shown) is to providediscrete magnets recessed into cover 310 on its enclosure-facing sidethat are positioned to be abut flange 304 and be held by the magnetsagainst it.

While port assemblies of the types described above (i.e. items 10, 200)may be used for cover 310 for insertion of a cleaning lance such aslance 12, cover 310 is shown with port assemblies 340 of a further type.Cover 310 has multiple openings 330 each covered (on the outer side ofcover 310) by a movable cover 332, as shown in FIGS. 18 and 19. Movablecover 332 acts as a restriction to flow and possible particulate leakagethrough opening 330 when the port assembly 340 is not in useaccommodating a lance 12. Openings 330 are bevelled at 331 toaccommodate a range of angular movement of lance 12. Each cover 332 issupported on a pivot pin 334 so as to be freely swingable about an axis336 by a user to uncover the associated opening 330. A cleaning lancesuch as cleaning lance 12 can then be inserted through the opening 330in the same way as shown in FIG. 1(a) for use in blowing gas intointernal space 302 to dislodge particulates therein. Thus, eachcombination of an opening 330, cover 332 and pivot pin 334 amounts to aport assembly 340 analogous to a port assembly 10. Port assemblies 340are simpler than port assembles 10 and 200 and are suitable for usewhere it is intended that the internal space of a cabinet (or otherenclosure) being cleaned will be held at a lower pressure than thesurroundings of that cabinet enclosure. The low pressure at least limitsany escape of particulates from the space 302 through port assemblies340. Although not shown, it would be possible to provide a seal (forexample an O-ring) surrounding opening 330 in either cover 332 or cover310 to better seal cover 332 against cover 310 when the pressure islower in the internal space than outside.

Cover 310 is shown as made from a sheet of transparent or at leasttranslucent material, which is advantageous because a user has bettervisibility of what is happening inside the enclosure being cleaned.Suitable polycarbonate plastics materials can be used, for example, andmay be treated with a scratch-resistant treatment as known in the art.Alternatively (not shown) a window (similar to window 88) may beprovided, with cover 310 being otherwise non-transparent.

Cover 310 is shown with an outlet port 346 similar to outlet port 18 ofFIG. 1(a), for connection of a duct (not shown) to be held at lowpressure and receive gas and entrained particulates gas from theenclosure being cleaned.

FIG. 24 shows a cover 310 a that is an alternative version of the cover310 also positioned ready for securing to cabinet 300. Parts of cover310 a that are, and that function, the same as corresponding parts ofcover 310 are indicated by item numbers including the suffix “a” and arenot described again here. Cover 310 a has several differences from cover310, as follows. First, cover 310 a comprises a central portion 311 andtwo side portions 313 and 315, that are hinged to central portion 311 by“piano”-type hinges 319 and 317 on the outward-facing side of cover 310a. This enables cover 310 a to be folded, so as to be easier than cover310 for one person to carry. (However, it is to be noted that hingessuch as 317 and 319 preferably avoided where folding is not necessary ashaving no hinge is simpler.) Formation 312 a is shorter than formation312 of cover 310, extending only along a top edge of portion 311, toenable folding. Second, cover 310 a has no attached seal correspondingto seal 318 of cover 310. Instead, a seal 321 is secured to, and extendsaround, flange 304. This may be either a pneumatic seal with aninflating connection 323, as shown, or a non-pneumatic elastomeric seal(not shown). To provide an adequate seal on cover 310 a itself insteadof flange 304, would be problematic due to the feature of folding. Thechain-dotted outline 321 b in FIG. 24 does not represent an actualcomponent, but the area on cover 310 a that is contacted by seal 321when cover 310 a is secured on cabinet 300. Note: cover 310 a is shownwith a different number and arrangement of port assemblies 340 a fromcover 310, but this is simply a matter of choice for any particularapplication.

While various embodiments of cabinet doors and enclosure covers havebeen described above, it is to be understood that particular features ofany one may where practicable be combined with features of another. Forexample, LED lighting may be used in any of the designs described above,as may any of the port assemblies 10, 200 or 340 or the “dished” shapeof cover 152.

Instead of a manually-manipulated and operated cleaning lance 12, somefurther embodiments provide for mechanical means for moving gasnozzle(s). Examples will now be given.

FIG. 20 shows an enclosure 100 in a view equivalent to FIG. 1(a).Nozzles 102 are mounted to, and able to rotate on, manifolds 104 thatare in turn secured by brackets 106 to door 108. Manifolds 104 aresupplied with gas from an external source (not shown) via conduits 110that extend through door 108. Rotating seals (not shown) enable gas toflow from manifolds 104 into nozzles 102 even as nozzles 102 oscillateabout manifolds 104. Conduits 106 are connected to an external manifold112 on door 108. A rotating crank member 114 connects via a link 116 toa link 118 that can oscillate nozzles 102 about manifolds 104 through arange of angles as shown by arrows 120. Crank member 114 extendssealingly to the exterior of enclosure 100 and is rotated manually or bya motor (not shown). Gas with entrained particulates is drawn fromenclosure 100 through a duct 122 equivalent to duct 20 of FIG. 2. Thereare several nozzles 102 on each manifold 104. Alternatively, an “airknife” type nozzle, not shown, elongate along the length of eachmanifold 104 may be provided instead of nozzles 102.

In a still further alternative shown in FIG. 21, a single “air knife”124, so-called, that is elongate across the width of an enclosure 126may be provided and arranged to be fed with gas from an external supplyand to produce a flow of the type shown by arrows 128 in FIG. 21, withthe air knife 124 being able to traverse up and down (as shown by arrows130) and to oscillate around an axis 132 extending lengthwise of the airknife 124. A suitable mechanism (not shown) could readily be provided bya person skilled in the art and enable such motions to be provided. Duct134 extracts gas and entrained particulates from enclosure 126.

In each of the arrangements shown in FIGS. 20 and 21, the systemexternal to the enclosures 100 and 126 is the same as system 30described above except for absence of cleaning lance 12. However, thearrangements shown in FIGS. 20 and 21 may even be provided withmotorized and automatically controlled positioning of the nozzles (102or air knife 124), and this may be under the control of microprocessor200 or a separate microcontroller (not shown). Positions andorientations taken up may be chosen that are well suited to the specificcomponents in the enclosure being cleaned, and their locations.

An embodiment will now be described that provides for cleaning of anopen-top rail car (for example of the type used for transport of coal orother minerals) or the like, and that involves essentially the sameprinciple as the embodiments described above. A problem with such railcars is excessive particulates remaining in the car after emptying,these particulates later being disturbed when the empty car is in motionand so polluting the environment.

FIG. 22 shows a typical open top rail car 400 whose upper part,comprising a load containing space 402, is shown in longitudinalsection. A tubular-section rail 404 extends around the top of the railcar. At a location where the car 400 is to be cleaned, a platform-likecover 410 is provided that when cleaning is to be carried out can bepositioned over car 400 and lowered (in the direction of arrows 406)onto the rail 404 from above, whereby to close space 402. An elastomericseal 412 contacts rail 404 after such lowering.

A carriage 412 moves lengthwise of the car 400 on a rail 414 (propelledfor example by an air motor (not shown)) and has mounted thereon one ormore nozzles 420 for blasting internal surfaces of space 402 with air(or other gas) supplied through a hose 416 and gas inlet 418.

To remove air (or gas) and entrained particulates from space 402, one ormore ducts 422, of which four are shown, are provided on the undersideof platform 410 and extend downward into space 402. Ducts 422communicate with a manifold 424 from which air (or gas) and entrainedparticulates are drawn at 426 by a vacuum source (not shown). Internalspace 402 may be kept during cleaning at a pressure below atmospheric.

When cleaning is complete, cover 410 is lifted upward to clear rail car400. The arrangement shown in FIG. 22 may be used in a building (notshown) with ends through which cars 400 (or other vehicles whereapplicable) are sequentially driven with lifting of platform 410effected by a fixed lifting equipment in the building. Alternatively, atruck or specialized vehicle (not shown) with a pivoted or articulatedarm may be used to manipulate platform 400 and associated equipment asrequired for cleaning.

Other types of container or enclosure are not open-topped but ratheropen at an end. As an example, FIGS. 25 and 26 are longitudinal centralsections on standard shipping containers. (Some detail of thesecontainers has been omitted, including doors.)

In FIG. 25, container 600 is closed by a cover 602 that fits into itsopen end when the outward-opening doors (not shown) are opened. Cover602 is sealed against gas and particulate movement by a peripheral seal604 that extends wholly around cover 602 and seals against innersurfaces (floor 606, walls 608 and ceiling 610) of the container 600.Seal 604 may be a pneumatically inflated seal. Sealing is not againstend surfaces of container 600 because of the presence thereon of latchfittings (not shown). In container 600 is a support carriage 612 movableunder user remote control on wheels 614, and that has a gas nozzle 616that can be remotely controlled by a user, outside container 600, tomove in a range of ways, as indicated by arrows 618. Gas is supplied tonozzle 616 by a conduit 620 (including a hose portion) connected throughcover 602 to a gas source (not shown) so that a jet of the gas can beused to dislodge and entrain particulates. Carriage 612 is also fittedwith at least one inlet 622 for gas and entrained particulates, that inturn is connected via a flexible outlet duct 624 to a system (not shown)equivalent in function to system 30 of FIG. 2. A window 623 is providedin cover 602 so that the user (not shown) can see and guide the carriage612 as required until the monitored concentration of particulatesleaving the container 600 is sufficiently low. Suitable lifting andmanipulation equipment (not shown) is provided for positioning carriage612 and then cover 602 for use, and for subsequently removing them fromcontainer 600.

FIG. 26 shows an alternative arrangement in which a cover 626 is fittedinto an end of a shipping container 628 in essentially the same way ascover 602 is fitted to container 600. A pneumatic or other suitable seal603 equivalent to seal 604 is provided to prevent escape of gas andparticulates around the periphery of cover 626. A nozzle 629 directs ajet of gas to dislodge and entrain particulates in the same way asnozzle 616 and is movable under user remote control in a range of waysas indicated by arrows 630. A gas supply (not shown) external to cover626 is provided and supplies nozzle 629 through a hose 631. Nozzle 629is supported in this embodiment by a structure 633 secured to cover 626.This is shown as a multi-section telescopic arm, but other arrangementswill readily suggest themselves to persons skilled in the art. Exhaustinlets 632 are provided on a structure 634 that is also secured to cover626 and that incorporates outlet ducting for gas and entrainedparticulates. A window 635 is provided in cover 626 for a user outsidecontainer 628. Not shown in FIGS. 28(a)-(c) is a system equivalent infunction to system 30. Suitable manipulating equipment (not shown) isprovided to enable cover 626 and the components secured to it to beentered longitudinally (i.e. in the direction of arrow 637) intocontainer 628 and later removed.

Although standard shipping containers have been referred to in relationto FIGS. 25 and 26, other types of enclosures could be suitable forsimilar arrangements. For example, some road vehicles (not shown) haveenclosures with end doors, and the arrangements shown in FIGS. 25 and 26could apply to them.

FIG. 27 shows a still further application similar to that describedabove by reference to FIG. 26. A container 650 (such as for example aplastics barrel of the type used for solid-phase chemicals) istemporarily closed by a cover 652 that is sealed to the container 650 bya suitable peripheral seal 654 (pneumatic or otherwise). Cover 652 has agland 656 through which there passes sealingly a gas inlet duct 658through which an external gas source (not shown) supplies gas to anozzle 660 within container 650. Nozzle 660 is able to be movedangularly as shown by arrow 662, and the duct 658 is able to be bothtraversed up and down (as drawn) and rotated as shown by arrows 664 and666 respectively. The movements of the nozzle 660 and duct 658 arecontrolled either by an automatic mechanism (not shown) or manually by auser whereby a jet of gas from nozzle 660 can be directed over theentire internal inner surface 668 of container 650. Also extendingthrough the cover 652 into container 650 is an outlet duct 670 throughwhich gas and entrained particulates are drawn out. Also provided is asystem (not shown) equivalent to system 30, for providing gas to duct658 and drawing out, treating and monitoring gas and articulates flowingthrough duct 670.

FIG. 23 shows an assembly 500 usable in some embodiments of the system30 shown in FIG. 2, specifically comprising elements 40, 42 and 46.Assembly 500 comprises a firstly centrifugal fan (blower) 502corresponding to blower 46 in system 30. Fan 502 is coupled to anddriven by a shaft (not visible) of an electric motor 504. Gas entersassembly 500 through an inlet port 506 after leaving cyclone separator38 and so contains less particulates than at outlet 18. From inlet port506 the gas enters a plenum chamber 508 and then passes through a filterbag 510 that is supported by a ring 512 at its upper end in acylindrical casing 514 which is shown partially sectioned. Filter bag510 corresponds to filter 40 of system 30 and may comprise a woventextile or unwoven material (as known in the filter art) suitable forcatching particulates while the gas passes through it and into an outerspace 520 of casing 514. From space 520, the gas then enters a modularHEPA filter 518 (corresponding to element 42 in FIG. 2)), thereafterpassing into fan 502 and out through outlet 536 (corresponding to outlet53 of system 30). Casing 514 may advantageously be formed from atransparent plastics material so that any fouling of space 520 byparticulates becomes apparent to a user.

Removal of filter bag 510 for emptying or disposal can be effectedthrough a lid 522 at the top (as drawn) of the plenum chamber 508. Bag510 is preferably of conical shape and proportioned to at leastapproximately equalize along its length the flux of gas through itssurface.

To hold the parts of assembly 500 together securely and sealinglyagainst gas and particulates leakage and enable easy disassembly whenrequired, casing 514 is fitted with a flanged ring 524 and a base plateor ring 526 is provided at an end of motor 504. Spaced circumferentiallyaround and extending between and through ring 524 and plate (or ring)526 are several (for example three) tension members 528 which onceplaced in tension hold together the fan 502 and motor 504, HEPA filter518, and casing 514. Members 528 may be for example solid rods threadedat each end for nuts or (as shown) lengths 530 of wire rope withthreaded end fittings 532 swaged on at each end and secured by nuts 534.

Motor 504 has its own integral air pump (not shown) for cooling withinlet 536 and outlet 538 separate from the gas flow circuit of system30.

Assembly 500 is convenient for some embodiments and applications,including where components of system 30 are provided in a backpack (notshown).

Yet another cover 310 c, shown in FIG. 29 and similar to cover 310 a(shown in FIG. 24) will now be described. Cover 310 c has a number offeatures that differ from features present in cover 310 a. Parts ofcover 310 c that are, and that function in essentially the same ascorresponding parts of cover 310 a are indicated in FIG. 29 by itemnumbers that are the same as those corresponding parts with an addedsuffix “c” so as to not need further explanation. Thus for example items312 ac in FIG. 29 do for cover 310 c what items 312 a do for cover 310a, namely allow cover 310 c to be hooked over an upper part of a flangeof a cabinet (not shown).

Instead of being made in three panels 313, 315 and 311 connected by twohinges, cover 310 c has two panels 802 and 804 connected by a singlehinge 806. (Of course, hinge 806 may be omitted altogether wherefoldability is not required.) Panels 802 and 804 are flat and may be ofa suitable translucent or transparent sheet plastics material. Portassemblies 340 ac are provided, but in different locations from the portassemblies 340 a of cover 310 a that facilitate folding of the twopanels 802 and 804 flat against each other when cover 310 c is not inuse. Not shown, but another possibility, is to provide port assemblies340 ac in locations tailored to allow best access to items (not shown)in enclosures on which cover 310 c will in use be deployed.

FIG. 30 shows a particular port assembly 808, comprising a cover portion810 that threadably engages with a collar 812 secured gas-sealingly topanel 802. Cover portion 810 can be screwed into or out of collar 812 asrequired using handle formations 816 and has an opening 814 that allowsa lance (such as lance 12) to be pushed into an enclosure (not shown) onwhich cover 310 c is secured. The other port assemblies 340 ac havecollars (not shown) the same as collars 812 and cover portions 818 thesame as cover portion 810 except that no opening corresponding toopening 814 is provided. These cover portions 818 have annularelastomeric seals (not shown) the same as seal 820 of cover portion 810.

Instead of a single port for extraction of gas (like port 346 a of cover310 a) cover 310 c has two ports 821 and 822 that are in fluidcommunication with chambers 823 and 824 on the sides of panels 802 and804 respectively that in use of cover 310 c lie in the opening of anenclosure (not shown) to be cleaned. Chambers 823 and 824 have internalspaces 825 and 826 respectively. (Chambers 823 and 824 are shown in FIG.29 as they would be seen through transparent panels 802 and 804.)

Chamber 823 (the same as chamber 823) is shown in section in FIG. 31.Space 825 is defined by walls 827, 828 and 829. Wall 828 has elongateslots 829, so that entry of gas and entrained matter is through multipleslots 829 as shown by arrow 830. This arrangement provides for betterremoval of entrained matter than a single position port such as 346 a.Item 831 is a portion of an enclosure to which cover 310 c could besecured for use. Flexible duct 832 (corresponding to duct 20 of FIG. 1)is shown in FIG. 31 as positionable sealingly by an end fitting 833enterable into port 821. Because there are tow ports 821 and 822, twosuch ducts are required and may be joined into a single flexible duct(not shown) by a suitable fitting. The essential here is that gas andentrained particulate matter can be collected at multiple points with anenclosure being cleaned.

Still further arrangements for effective removal of gas and entrainedparticulates will readily suggest themselves to persons skilled in theart.

Referring to FIG. 2, in practical realisations of the invention, many,most or all of the sensors provided may be in an enclosure that isseparate from the enclosure being cleaned and connected to the latter bythe conduits 34 and 20. However, the measurement of pressure with theenclosure being cleaned is particularly important and sensing of thatpressure is desirably done at a point within the enclosure beingcleaned. As an alternative to a sensor at a station such as station Cwith an electrical connection for its output to an enclosure containingthe other components left of station “XX” in FIG. 2, it is possibleinstead to provide an orifice opening into the enclosure being cleanedand in fluid communication through a flexible tube with a sensor(pressure transducer) located in the enclosure containing those othercomponents. FIGS. 32 and 33 show two ways to do this.

FIG. 32 shows an enclosure 900 being cleaned, with a duct 901(corresponding to duct 20 of FIG. 2) connecting the interior ofenclosure 900 to an enclosure 902 containing the components shown to theleft of station “XX” in FIG. 2. Duct 901 is of the known type having aflexible tube 910 held open by a spiral formation 911 such as a wire.

A small-diameter tube 904 enabling an orifice 905 open to the interiorof the enclosure 900 to connect to a sensor 906 in enclosure 902 mayconveniently be provided inside the flexible duct 901, with the tube 904terminating in the orifice 905 in a fitting 903 by which the duct 901 issecured to the enclosure 900. At its other end, tube 904 terminates at afitting 913 with a passage 914 in fluid communication with a pressuretransducer 906 in enclosure 902.

Another possibility is to eliminate tube 904 and provide instead thatthe duct 901 is again of the type having a flexible tube 910 held openby a spiral formation 911, but in which that spiral formation is itselfhollow along its length, so as to be in effect a small-diameter tube.The orifice 905, in fitting 903, is in this case in fluid communicationwith the hollow interior (not shown) of the spiral formation 911. At theother end of the duct 901, the spiral formation 911 and its interior(lumen) is in fluid communication via passage 914 in fitting 913 withthe pressure sensor 906 in enclosure 902.

In each of these two arrangements, it is appropriate to provide at theorifice that opens into enclosure 900 a plug or cover, for example ofsintered metal, (not shown) adapted to prevent clogging of the orifice,which could adversely affect the pressure measurement.

To disclose yet further additional options for covers according to theinvention, FIG. 33 shows a cover 310 b that is an alternative to covers310, 310 a, and 310 c. Cover 310 b comprises a single transparentplastics panel 1024 shaped and proportioned to fit over an opening intoan internal space of an enclosure (not shown). Cover 310 b is providedwith multiple ports 1012 of the type shown in FIGS. 18 and 19, locatedspecifically in positions that provide optimal access for a cleaninglance such as lance 12. There is also a port 1020 that in use of thecover 310 b receives an end fitting 1026 of an outlet conduit 1002 forgas and entrained particulate matter that corresponds in function toconduit 20 of FIG. 2.

Banks 1018 of light emitting diodes (LEDs) are provided on theinternal-space-facing face of panel 1024 for internal lighting of theinternal space. The LEDs are protected by transparent or translucentelongate covers glued or otherwise secured to panel 1024. Extendingaround the periphery of panel 1024 is a seal 1016 that in use of cover310 b lies between panel 1024 and a facing part of the enclosure beingcleaned. Seal 1016 may be formed from rubber or a rubber-like materialor other material (for example felt) to provide at least some degree ofsealing against gas and particulate leakage as cover 310 b is pushedagainst the enclosure by the difference between atmospheric pressure andthe partial vacuum maintained in the enclosure. Perfect sealing is notessential where there is a p[atrial vacuum in the enclosure.

Two additional provisions are made for holding the cover 310 b in place.First, magnets 1014 are secured in recesses in panel 1024 and pull panel1024 toward the enclosure (if it is ferromagnetic). Second, a formation1010 is provided whereby the cover 310 b can be hooked onto an upperedge of a flange (not shown) on the enclosure, in the same way asdescribed for covers 310 and 310 c.

Two forms of sensor are provided on cover 310 b. First, a pressuresensor 1022 is provided for sensing pressure inside the enclosure,having a pressure-sensitive diaphragm or surface (as opposed to a smallhole leading to such diaphragm or surface) so as to be immune fromclogging with particulate matter. Second, at each port 1012 there isprovided a sensor (not shown) that indicates whether the port is “open”(i.e. in use to accommodate a cleaning lance such as lance 12) orclosed. The sensor may be of any suitable type (for example amicroswitch or a Hall effect proximity sensor.

To direct power to the sensors and LED banks 1018 and to allowtransmission of their outputs to other parts of the system a connectingcable 1004 is provided that is secured (at 1006) by tape, suitable clipsor the like to duct 1002. Necessary electronics, signal conditioning forthe sensors and power connections (not shown) are protected in a housing1008 secured to panel 1024, at which an end of cable 1004 terminates.Note that with suitable end fittings for outlet conduit 1002, it ispossible to run cable 1004 inside conduit 1002, thus reducing the riskof damage to cable 1004.

As an alternative to cable 1004, it is possible to provide for signalsfrom the sensors on cover 310 b to be transmitted to the rest of thesystem by a short-range wireless connection for example using the“Bluetooth” or “Bluetooth Low Energy” or other suitable protocol. Inthis case, housing 1008 may contain a battery for supplying power to thesensors as required and to the LED banks 1018. Note that as a furtheralternative, the functions of housing 1008, pressure sensor 1022 may beprovided in a housing secured temporarily or even permanently to theenclosure to be cleaned.

Note also that in embodiments where the pressure sensor for internalspace pressure is to be located elsewhere in the system and connected toa tapping in a cover such as 310, 310 b or 310 c, a flexible tube can beprovided terminating at a tapping in the cover and secured along duct1002 as shown in FIG. 33, although such embodiments are not preferred.

Outlet conduit 1002 (or other outlet conduits described herein) thatcorrespond to outlet conduit 20 of FIG. 2 are preferred to have smoothinner wall surfaces to avoid fouling with particulate material. Thuswire reinforced hose having a non-smooth inner surface is less preferredthan hose with a smooth inner wall surface.

Example of the System

A prototype system according to the invention was developed and hasproved satisfactory for cleaning electrical component cabinets on largesurface mining haul trucks. The system used a conventional reticulatedworkshop air supply as its gas source (item 32 of FIG. 2) and thecomponents to the left of station “XX” in FIG. 2 (excluding selector 50which was not included) and were able to be accommodated in asuitcase-sized plastics casing 1030 suitable for carrying as a backpack.FIG. 34 is an elevation showing how the major components (only) wereable to be accommodated in the casing. Casing 1030 is shown without itslid, which is hinged at moulded fittings 1050.

A cyclone corresponding to cyclone 38 of FIG. 2 is shown at 1036, withits inlet for gas and particulates drawn from enclosures shown at 1034.Item 1042 is a container inside which is a receptacle (not shown) forcollection of particulates received from the cyclone at 1036, thereceptacle being emptiable when an ultrasonic transducer pair (senderand receiver, not shown) provides a signal indicating it is full.

At 1038 is a duct from the cyclone at 1036 leading to a cylindricalcasing 1040 containing firstly a disposable paper bag-type filter (notshown in FIG. 34) receiving gas and unremoved particulates from the ductat 1038, and secondly a HEPA filter downstream of the paper-bag-typefilter. At 1032 is a screw cap for accessing the interior of casing 1040for removal and replacement of the paper-bag filter and removal andservicing of the HEPA filter.

The source of vacuum for drawing gas and particulates through the systemis shown at 1044 (casing for a centrifugal or blower fan (not visible)and 1048 (motor for the fan). Gas leaves the system via a muffler 1046via a port (not visible) at the left side of the casing 1030.

Not shown in FIG. 34 are triboelectric sensors for sensing particulateconcentration at locations corresponding to stations F and K of FIG. 2.Electronics componentry (not shown) is housed in the lid (not shown) ofthe casing 1030. Pressure transducers for locations corresponding tostations C, F, G, H and I of FIG. 2 are mounted on a printed circuitboard in the lid and connected to those locations by small-bore flexibleplastics tubes.

Also housed in the lid is a relay-operated valve corresponding to item52 of FIG. 2 for controlling gas supply to the lance (not shown), and inparticular shutting off that supply if pressure in the enclosure beingcleaned rises to become too close to pressure in the surroundings (i.e.if there is a risk of loss of partial vacuum in the enclosure beingcleaned).

FIG. 35 shows the casing 1030 in the same elevation as FIG. 34 but nowwith screw cap 1032 removed and a filter bag holder 1052 removed fromcasing 1040 as is required for emptying. Bag holder 1052 (shown in FIG.36) comprises a plastics moulding in which vertical bars 1041 arearranged in a circle supported by circular parts 1057. No filter bag isshown in FIG. 36, for clarity. As can be seen in the sectional view ofFIG. 37, bars 1041 lie adjacent to the wall of casing 1040 when holder1052 is placed in casing 1040. Filter bag 1045 is held away from thewall of casing 1040 by bars 1041 when, in use, there is gas underpressure in bag 1045. This ensures that between each pair of adjacentbars 1041 there is a space 1047 into which and down which gas passingthrough bag 1045 can pass as shown by arrows 1043. Holding the bag awayfrom casing 1040 in this way ensures that a large portion of the bag'ssurface is available for catching particulate material entrained in thegas in the bag 1045. Item 1059 defines a space above the HEPA filter(not shown) so that its whole cross- sectional area is used.

The filter bag used in holder 1052 in the prototype is a commerciallyavailable porous paper filter bag having a circular opening. Gas andparticulates enter the bag through a short duct 1051 that is separatefrom holder 1052 but is received therein as shown. A seal 1049 isprovided on duct 1051 that when the bag is placed in holder 1052 sealsagainst the inner wall of casing 1040.

A further possible refinement of the invention will now be described. Inthe description supporting FIG. 3, mention was made of sensors for thestate of the various ports 1012. The functionality of FIG. 3 may beexpanded to include sensing of the state of ports 1012 during a cleaningsession, to provide to supervisors and/or others an indication of howthe operation was carried out. For example, were all of ports 1012 usedat some point? For how long? Moreover, it is possible to provide throughsystem 199 a defined sequence to be followed in cleaning a particularenclosure and to display prompts to an operative as to that sequence atblock 208.

Still another possible refinement is to expand the functionality of thesystem as shown in FIGS. 2 and 3 to provide for data to be received fromsensors of operator comfort, for example temperature at the worksite orinside protective clothing of an operative carrying out a particulateremoval operation.

In the above descriptions, many specific embodiments have beendescribed. However, it is to be understood that features of thoseembodiments may be used where practicable in other combinations thanthose explicitly shown to suit particular circumstances. For exampleonly, other embodiments may include features selected from at least thefollowing non-exhaustive list:

-   -   Covers for enclosures may be permanent or adapted for temporary        use, may be produced by modifying existing doors or other        closures or made new to provide for cleaning as described, may        be transparent or not, may have viewing windows or not, may be        “dished” (as in FIG. 14) or not, may have LED or other lighting        provided in the enclosure or incorporated in the cover used.        Covers may be secured in place by hanging from existing or        dedicated parts of enclosures to be cleaned or not, and/or by        clamps of any type described or other suitable types, or partly        or wholly by maintenance of below-atmospheric pressure in the        enclosure. Contact between the interior space and the cover need        not be on a plane, even though the particular embodiments        described do have that property. Where covers are transparent or        have transparent portions, anti-scratch treatments as known in        the art may or may not be applied.    -   Sealing arrangements for covers may be pneumatically inflated or        not, and may be secured to a cover or on the enclosure to be        cleaned.    -   There may be one or several outlet ducts for gas and entrained        particulates.    -   Port assemblies of any of the types described (items 86, 158,        200, 340), or others that allow introduction to the enclosure of        a cleaning lance without excessive leakage of particulates        and/or gas, may be provided in a cover used as described. It is        even possible, where pressure in the enclosure being cleaned is        always kept below atmospheric during cleaning, to simply provide        holes in a cover through which a cleaning lance can be inserted.        Ports of different types (including those described herein) may        be used in combination in one cover.    -   Any or all of the sensor types mentioned, or other types known        in the art and consistent with the functions described may be        used, in the locations shown or other suitable locations.    -   Pressure in an enclosure being cleaned may be automatically or        manually controlled.    -   Movement of cleaning lances or other fittings (such as the        nozzle arrangements shown in FIGS. 20 and 21) may be automatic        or manual. Note that in some applications, it may not be        necessary for gas nozzles to be movable at all, to achieve        adequate cleaning for particular purposes.    -   Separation technologies for removing particulates from gas        streams (e.g. textile bags or other filters or cyclones may be        provided in suitable numbers and/or combinations.    -   Any suitable means of supplying gas for cleaning may be used and        gas may be used once or recycled within the system. For example,        gas from outlet 53 in the arrangement shown in FIG. 2 may be        recycled, in whole or in part, to constitute or be comprised in        gas source 32.

The apparatus and methods described herein may be adapted to removal ofparticulate matter from various entities, with various geometries. FIG.28(a) represents schematically applications of the type disclosed above,showing in section a cover 700 (corresponding to cover 310 for example)is fitted over an opening 702 of a cavity 704 in an object 706. Item 708is a cleaning lance (similar to lance 12), items 710 are ports (similarto ports 340), item 712 is an outlet duct (similar to duct 20), and item714 is a seal (similar to seals 318 or 321).

FIG. 28(b) represents schematically an application to removal ofparticulate matter from a surface 716. Hood 718 (shown in section) ispositioned to abut surface 716 with a seal 728 extending around the areaof surface 716 covered by hood 718. Cleaning lance 722 extends throughone of several ports 720 in hood 718. 726 is an enclosed space definedbetween surface 716 and hood 718. An outlet duct 724 is provided forremoval of gas and particulate matter.

FIG. 28(c) represents schematically an application where an object 730is to have particulate matter received and is covered for the purpose bya cover 734 that abuts a surface 732. Cleaning lances 736 extend throughports 738 and are moved as required. Seal 740 limits or prevents leakagebetween cover 734 and surface 732.

Although examples (a), (b) and (c) all show covers (700, 718, 734) thatcan abut a flat surface, this is not essential. Where an applicationrequires it, the boundary between cover and the entity it abuts in useneed not be planar.

Note also that the object 730 could be an object, or surface 732 couldbe a surface, on which some particulate-generating process is beingcarried out, for example sanding, grinding or “scabbling”. Although notshown, the apparatus and methods described may be adapted to contain,and enable removal of, particulates in such cases also, for example byproviding an extra access port in the cover for equipment used in theprocess or for the arm of an operator reaching into the cover.

Note finally that covers according to the invention need not necessarilybe shaped to cover a flat surface (such as a flange around an opening ofan electrical cabinet). Covers for performing the invention (in the sameway as covers 310, 310 a, 310 b and 310 c) may be contoured to suitother enclosure geometries. For example, large electric motors (notshown) s may have openings for access to brushes and commutators, andthese are components that may need to be cleaned. It is possible to makea cover similar for example to cover 310 b (FIG. 33) save that it isarcuately shaped to cover such an opening during cleaning. In this case,however, ports such as ports 1012 and port assemblies 340 areunsuitable. However, port assemblies of the type shown in FIG. 4 can beused, with at least one slit disc (the same as disc 94) having its slit(corresponding to slit 96) parallel to the motor shaft.

1. Apparatus for removing particulate matter from an enclosure having aninternal space and an opening into the internal space, comprising: acover positionable adjacent the opening so that the cover covers theopening; a gas source external to the internal space; an inlet conduitthat in use extends through the cover and is adapted to direct gas fromthe gas source to a gas outlet within the internal space wherebyparticulate matter within the internal space is dislodged and entrainedin gas within the internal space; a source of partial vacuum adapted tomaintain a partial vacuum within the enclosed space and to draw gas andparticulate matter entrained therein from the internal space firstlythrough an outlet conduit and then through a particulate matterseparation means comprising at least one filter; a sensor for sensingconcentration of particulate matter in gas leaving the enclosed space; adisplay adapted to provide to a user information on concentration ofparticulate matter leaving the internal space so that the operator cancontinue use of gas from the gas source to dislodge particulate matterin the internal space until a satisfactory value of the concentration isachieved.
 2. Apparatus according to claim 1 wherein the outlet conduitis in use secured to the cover and draws gas through an opening in thecover.
 3. Apparatus according to claim 1 wherein the gas outlet ismovable relative to the cover among multiple positions within theinternal space.
 4. Apparatus according to claim 3 wherein the gas outletis at an end of an elongate tubular lance comprised in the inletconduit, the lance in use extending though a port in the cover so that aportion of its length is in the internal space and the user can manuallymove the lance to cause the gas outlet to take up any of the saidmultiple positions within the internal space.
 5. Apparatus according toclaim 4 wherein the port in the cover is one of a plurality of ports inthe cover said ports so positioned that the user can withdraw the lancefrom one port and enter the lance into another port as required toaccess multiple parts of the internal space.
 6. Apparatus according toclaim 5 wherein each of the plurality of ports is adapted to restrictflow of gas and particulates therethrough when the port does not havethe lance extending through it.
 7. Apparatus according to claim 1further comprising control apparatus for stopping flow of gas from thegas source to the gas outlet by the user.
 8. Apparatus according toclaim 7 wherein the control apparatus is operable automatically inresponse to sensed pressure within the internal space rising to apredetermined threshold level to interrupt flow to the gas outlet. 9.Apparatus according to claim 1 further comprising a sensor for sensingconcentration of particulate matter in gas discharged from the apparatusdownstream of the source of partial vacuum.
 10. A method for removingparticulate matter from an enclosure having an internal space and anopening into the internal space, comprising the steps of: positioning acover adjacent the opening so that the cover covers the opening;providing a gas source external to the internal space; providing aninlet conduit that in use extends through the cover and is adapted todirect gas from the gas source to a gas outlet within the internal spacewhereby particulate matter within the internal space is dislodged andentrained in gas within the internal space; providing a source ofpartial vacuum adapted to maintain a partial vacuum within the enclosedspace and to draw gas and particulate matter entrained therein from theinternal space firstly through an outlet conduit and then through aparticulate matter separation means comprising at least one filter;providing a sensor for sensing concentration of particulate matter ingas leaving the enclosed space; using the sensor to derive and provideto a user information on concentration of particulate matter leaving theinternal space; using gas from the gas outlet to dislodge particulatematter in the internal space until a satisfactory value of theconcentration of particulate matter in gas leaving the enclosed space isachieved.
 11. A method according to claim 10 further comprising thesteps of: repeatedly sensing concentration of particulate matter in gasleaving the internal space during cleaning thereof and making digitalrecords thereof; time stamping each digital record and transmittingusing a digital data network the digital records to a remote locationfor recording and approval.
 12. A method according to claim 11 includingthe step of repeatedly sensing pressure within the internal space duringcleaning thereof and including in the transmitted digital records sensedvalues of pressure within the internal space.
 13. A method according toclaim 11 including the steps of: further providing a sensor for sensingconcentration of particulate matter in gas discharged from the apparatusdownstream of the source of partial vacuum; repeatedly sensingconcentration of particulate matter in gas discharged to atmospheredownstream of the source of partial vacuum and including in thetransmitted digital records sensed values thereof.